Device for dispensing liquid

ABSTRACT

A liquid dispenser ( 100 ) primarily for use in dispensing liquid drench to animals. The dispenser ( 100 ) is electronic in operation and has the ability to control the speed of its pump ( 5 ) according to environmental conditions including the viscosity of the liquid being dispensed.

TECHNICAL FIELD

The present invention relates to a device for dispensing doses ofliquid.

Reference throughout the specification shall be made to the use of thepresent invention in devices such as drench guns, injectors and the likethat are used for treating livestock with liquid medicament. While theprinciples of the present invention could apply to other situations, ithas been particularly developed for this field.

BACKGROUND ART

It is often desirable to treat livestock with drugs to controlparasites. Parasiticides (or drenches) are often applied to the skin (asa pour-on liquid) or administered orally. Livestock may also be injectedwith these drugs. To control parasites, the livestock typically must berounded up and placed in a holding area and separated by size so thateach animal may be properly dosed with the drug. Once treated, theanimal is released until the next dosing is required. Preferably arecord is made of the drug and dose administered and the date ofapplication.

Unfortunately, the process of separating the animals by size,administering the requisite dose to each size group of animals in turnand keeping manual records, is time consuming and expensive. This temptsthe farmer into overdosing an animal to prolong the period during whichthe drug is present at effective levels. Furthermore, to avoid thesorting by size the farmer may rely upon his judgment to estimate thedosage to administer to each animal.

It should be appreciated that dispensing liquid in a farm environment isquite a different proposition to that in a more controlled situationsuch in a laboratory or factory.

Firstly, the environment in which the operator works is quitechangeable.

For example, the reservoir holding the liquid (hereinafter referred toas drench) may be in a backpack on the operator. In other situationsthere may be a larger drench container situated on the ground, on avehicle or elsewhere.

All these different environments can affect the operational dispensingdevice as the varying volumes, heights (which can affect pressure head)and container shapes and conduits to the dispensing outlet can lead toinconsistencies in the amount being dosed by the operator.

This is obviously an undesirable situation given that relatively precisedoses of treatment liquid are required to ensure that the treatment iseffective and the animal is either not overdosed or underdosed.

Another situation which is fairly specific to the drenching of animalsis that quite often the same dispensing device is used to dispense avariety of treatment liquids, each having different viscosities or flowproperties. Thus, it can take longer to dispense a certain volume ofliquid having a high viscosity than the equivalent volume of a liquidhaving a low viscosity. This can be frustrating to the operator of thedispenser as often hundreds of animals are being treated at a time.

Whitford's New Zealand Patent No. 224789 describes a drench apparatuswhich attempts to overcome some of these difficulties by providing ananimal scale with a weight transducer which supplies a signal used toregulate a motorised drench dosage pump to dispense a dose in proportionto the animal's weight.

A disadvantage with this system is the necessity of providing the scale,which is expensive and relatively massive. Not being readily portable itlacks versatility and does not lend itself to use away from the normalholding area on the farm, where it would typically be permanentlyinstalled. Moreover, this known system requires manual record keepingand provides no indication of the progress of the dispensing operation,such as the number of animals treated.

Eidson Associates' New Zealand Application No. 332852 also attempts toovercome a number of these problems by providing an automatic drenchingsystem. This overcomes the problem of operator fatigue as an electronicswitch on the hand held drench gun activates a peristaltic pump whichpumps fluid through to the drench gun. However, this invention does notaddress a number of the problems in the prior art, including storage ofinformation, changing environmental conditions, fluids of differentviscosity and easy recalibration.

It is an object of the present invention to address the foregoingproblems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will becomeapparent from the ensuing description which is given by way of exampleonly.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided adevice for dispensing liquid which includes

-   -   a hand piece for dispensing the liquid,    -   a variable speed pump for pumping the liquid, and    -   communication means which enables the operator of the device to        alter the speed of the pump.

Reference throughout the specification should be made to the use of thedevice for dispensing the liquid for the treatment of animals in a farmsituation. It should be appreciated however that he device can be usedin other situations as well.

The liquid to be dispensed shall now be referred to as drench; howeverthis should not be seen as a limitation on the use of the device.

The hand piece for dispensing the liquid should now be referred to as adrench gun. Again, this term should not be limiting and other handpieces may be used including injectors and the like.

Preferably the drench gun is electronic in operation with an electronictrigger as well as a microprocessor for controlling the operation of thedevice.

In some embodiments the present invention includes a hand piececonfigured for use with the device.

In the preferred embodiment, the hand piece includes a trigger toactuate the dispenser, a keypad to enter data into the controller and adisplay. Preferably, the hand piece is lightweight and neutral tohandedness, being equally amenable to left-hand or right-hand operation.A conduit connecting the hand piece to the pump may be retractable forconvenience.

The variable speed pump is preferably a positive displacement pump.Preferably a gear pump is used as this has a number of advantages overother pumps. The applicant has found a gear pump which has acetylgearing that is less susceptible to degrading through the chemicalaction of the drench passing through the pump. For example, peristalticpumps require the use of soft tubing which can more readily degrade thanharder plastics.

Another problem peristaltic pumps have in common with syringe pumps isthat the liquid emerges in spurts over higher volumes. This is not adesirable characteristic for the operator of the device to cope with.

Syringe pumps also have the disadvantage in that they can also takelonger than gear pumps to pump the same amount of volume.

Another advantage of gear pumps is that they can be produced in a smallenough size to enable them to be readily carried by an operator in abackpack.

A further advantage of a gear pump is that it can be readily used tometer the amount of volume being dispensed.

Preferably, the variable speeds that the pump can operate are actuallypre-programmed into a control system for the operation of the dispensingdevice.

The communication means may take a variety of forms. In one embodiment,the drench gun includes communication means that communicates with thecontrol means of the pump or directly controls the pump. For example,the drench gun may include a transmitter which sends signals to the pumpor pump controller.

However, in the preferred embodiments the drench gun is hard wired tothe pump.

It is envisaged that in preferred embodiments, the operation of atrigger on the drench gun will cause the pump to operate thus dispensingfluid through to the drench gun. Preferably, the amount of volume beingdrenched can be selected by an operator through interaction with thesoftware/electronics of the drench gun.

This selection process may be via a key pad and/or screen on the drenchgun.

It is preferred that the initiation of the variable speeds of the pumpwould be via the operator interacting with the electronic drench gun.However, in some embodiments there may be a separate controller to thaton the drench gun.

The operator may wish to change the speed of the pump under a number ofcircumstances.

For example, the operator may have previously been dosing animals usingthe device with the drench carried in a backpack. This may apply acertain pressure head to the system. Conversely, if the same dispensingdevice is used in accordance with a liquid reservoir situated on theground there is no head of pressure. Therefore, in the latter situationit may be possible for liquid to flow back through the gear pump, thusdelivering a lesser volume of drench than in the backpack situation overthe same time.

Having regard to the foregoing, it would be an advantage to the operatorto be able to increase the speed of the gear pump when the dispensingdevice is used in situations with low pressure heads to centre theeffect of trickle back and give more uniform volumes over the same time.

In one embodiment of the present invention, the device may be programmedso that the operator may indicate to the device the environment (say viathe drench gun) in which the device is working which causes the pumpspeed to adjust accordingly.

The drench gun may also be programmed for the operator to be able toindicate to the device the type of drench being dispensed, whether it behigh, low or medium viscosity, or a proprietary drench. For example insome embodiments of the present invention particular drench names may beprogrammed into the drench gun.

Depending on the viscosity of the liquid identified as being dispensed,the pump speed may be operated by the controlling software of the deviceto ensure that the amount of time to dispense certain volume issubstantially the same for the various liquids.

A table showing how parameters of the operation of the device can chargewith different drenches is given below.

DRENCH VISCOSITY RPM Low 8,500 Medium 13,000 High 15,500

Having electronic controls associated with the device, and morepreferably with the drench gun itself, a number of features can be builtinto the present invention.

In some embodiments the device may transmit data to or receive data fromanother device, for example an ear tag scanner, barcode reader, or acomputerised farm management system. The data communicated may becontrol data relating to, for example, the requisite dosage for aparticular animal or performance data such as a running total of volumeof liquid dispensed.

It will be appreciated that the device may be adaptable to fullyautomate the keeping of records relating to animal drenching. In oneembodiment, the software may provide means for downloading records to acomputerised farm management system.

It should be further appreciated that in some embodiments a transceiverused within the present invention can be a mobile phone that can be usedto connect to a modem or similar device in order to download data to acomputer or in some cases upload data from the computer.

The present invention can also be readily used with electronic weighscales which can give feedback to the controller and help calculate thevolume of drench required for an animal of a certain weight.

Another aspect of the present invention there is provided a method ofcalibrating the volume of liquid dispensed by a device wherein thedevice includes a hand piece for dispensing liquid and a variable speedpump for pumping the liquid.

The method being characterised by the steps of

-   a) inputting into the device a desired volume of liquid to be    dispensed, and-   b) dispensing a volume of liquid from the device accordingly, and-   c) measuring independently the actual volume dispensed, and-   d) inputting into the device the actual volume dispensed or a    comparative volume with the desired volume inputted in step a), and-   e) using the differential between the desired volume and actual    volume to calibrate the operation of the device over a range of    volumes.

It is possible that in between different operations and environmentsthat slippage can occur with the desired volume as programmed into thedevice and the actual delivered volume. To address this the inventor hasdeveloped a calibration system as described above for calibrating thedevice at the start of an operation.

In preferred embodiments, the design of the device is such thatcalibration need only be undertaken once every day the device is beingoperated.

A significant advantage of the calibration method as described above isthat only a single data point is required to be entered into thesoftware of the device for recalibration to occur over a whole range ofvolumes. It can be appreciated that this can save considerable time.

Further, as the calibration method is implemented in software, there isno requirement for the operator to manually adjust settings on the pumpor other valves in the system.

A preferred algorithm by which the calibration method is described aboveis given below

EXAMPLE 1

Procedure Calibrate

{This procedure will write the new calibration to the product memory, aswell} {as set the current calibration to this selected product.}

-   Begin    -   Beep;    -   RdByteEE(LastProduct,Contents); (* Last product that was used is        read from extended endurance memory *)    -   IF Contents=255 THEN Contents:=3 (* Safety check to see if        pointer to memory location is not out of range put it in current        calibration position in memory. *)    -   Else Contents:=(Contents*3)+6; (* calculate the location in        extended endurance memory complete with offset relevant to        current product in use *)    -   Scratch:=ORD(Troix); (* find out if the amount is a positive        amount or a negative amount. Increment the amount or decrement        the amount. *)    -   IF (Scratch=0) THEN Begin (* Three bytes were sent out. The        third byte is the amount to correct, the second byte is the sign        indication *)        -   Alarm; (* if the amount to correct with is 0 than ignore the            rest of this algorithm and exit here. *)        -   EXIT;    -   End;    -   IF Scratch>=Lo(Dose) THEN Scratch:=Lo(Dose)−1; (* This statement        protects and avoids the number that was entered was bigger than        the original dose size. For example if a 10 ml dose was        corrected by 12 ml, then the amount to correct with is larger        than the original dose size    -   IF ORD(Deux)=255 THEN Begin {255 indicates negative sign, 0        indicates positive sign *)    -   IF (Dose>Scratch) Then Begin {only with a smaller correction}        -   MyReal:=(((Dose+Scratch)/Dose)* 100)−100;-   (* convert the calibration real number to the percentage reading. *)    -   Calib:=Calib+((Calib/100)*MyReal); {increase the calibration}    -   End {You can not subtract more than the dose}    -   End Else Begin (* indicates a positive amount *)        -   MyReal:=(((Dose+Scratch)/Dose)* 100)−100; {=Percentage more            wanted}        -   Calib:=Calib−((Calib/100)*MyReal); {Lower the calibration}    -   End;    -   Calib:=(Calib*100); (* conversion to the best fit 2 byte        representation to store in EEPROM *)    -   Handy:=Round(Calib); {Handy is a 16 bit word}    -   WrByteEE(Contents,Hi(Handy)); {Copy the high byte}    -   WrByteEE(CurrentCalib,Hi(Handy)); {Write calibration to EEPROM}    -   WrByteEE(Contents+1,Lo(Handy)); {Copy the low byte}    -   WrByteEE(CurrentCalib+1,Lo(Handy));    -   WrByteEE(Contents+2,SetSpeed); (* Store the current speed        setting with this calibration to recall back when read back        again *)    -   WrByteEE(CurrentCalib+2,SetSpeed);    -   Calib:=Handy;    -   Calib:=(Calib/100); (* Restore calibration value, a real number        *)    -   IF (Calib<0.1) Then Calib:=0.1; {safety not to go out of range        in ridiculous values *)    -   Dump(DipSwitch+80,Ord(‘c’),Ord(‘c’)); (* Confirm calibration was        done, send it to the gun and update it about which pump it came        from.*)-   End;

Most dispensing systems need priming at the start of any operation. Inpreferred embodiments of the present invention there is provided anautomated priming routine controlled by the software of the device. Inparticular, gear pumps can have problems in priming air from a system.For example, in the present invention there may be an actuator such asbutton or a selection that the operator can make, say on the drench gun,at the start of any operation. Pressing the prime button could cause thepump to operate and any valves within the device to open allowing fluidto flow through conduits to the system and out the gun until all or mostair is primed from the device. Activating the ‘Prime’ sequence couldalso ensure that any meters, counters or volume indicators aredeactivated.

In some embodiments of the present invention there may be providedadditional valving in the device to provide greater control of fluidflow and/or metering of fluid flow.

For example, in some embodiments there may be provided a valve situatedbetween the drench reservoir and the pump. This valve (preferably asolenoid valve for accurate control) could perform the function ofstopping excess trickle from the reservoir to the pump which can occurin particular when the present invention is used in a backpacksituation.

In some embodiments there may be provided a flow valve associated withthe drench gun. This valve can confirm whether actual drench has beendispensed. For example, the pump may operate and assume it is dispensingvolume, but not be connected to the gun itself or may only be pumpingair. The flow valve therefore provides more accurate metering.

The flow valve can also be used to stop problems of the trickle ofliquid through the system on account of head pressure.

In preferred embodiments there is provided communication between thedrench gun, pump and valves to ensure that the operation of each iscoordinated appropriately to ensure the smooth delivery of the drench.

The hand piece may be adapted for applying a drench to the skin of ananimal in a “pour-on” manner, and in one preferred embodiment of theinvention a “pour-on” hand piece is used with a backpack mountedcontainer and dispensing system.

Separate rechargeable batteries may be provided for power supply to boththe power pack, comprising the motor/pump assembly and to the handpiece. Alternatively means may be provided for connecting the power packto a suitable portable supply, such as the electrical system of atractor.

It will be appreciated that the dispenser is particularly adapted foruse administering drenches in either the pour on manner, orally or ininjected form. The dispenser can be readily drained for changing fromone medication to another and can also be quickly recalibrated toaccount for liquids of different viscosities.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from thefollowing description which is given by way of example only and withreference to the accompanying drawings in which:

FIG. 1 is a schematic of the metered liquid delivery device of thepresent invention, and

FIG. 2 is a diagrammatic top view of a drench gun in accordance with oneembodiment of the present invention, and

FIG. 3 is a diagrammatic view of a drench container, pump and drench gunin accordance with one embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

In FIG. 1 electrical/magnetic (including possibly wireless) connectionsbetween components are represented by dashed lines, while liquidconnections are represented by solid lines. The metered liquid deliverydevice 100 includes two main sub-components, power pack 1 and hand piece3 connected by discharge hose 4. A container 24, in which is kept aliquid drug composition is connected to the power pack 1. The container24 could be any number of devices including a tank mounted on a tractor,an easily portable twenty-litre container or a back pack mountedcontainer or the like. The container 24 has an atmospheric vent 14 and acoupling 15.

The liquid in the supply container 24 is pumped by a gear pump S, drivenby a motor 6. Optionally, the motor 6 may include a reducer gear (notshown) to match the motor 6 speed to the pump 5 requirements and themotor may be reversible. Electrical power is provided to the power pack1 components through a battery 7, or in alternative embodiments anotherpower supply such as the mains.

The liquid is drawn from the supply container 24 through a suction hose8 by the gear pump 5 and then pumped through a discharge hose 4 to arestrictor valve 9 on the outlet of the hand piece 3. The restrictorvalve 9 is a flow control valve, of a normally closed spring-loaded typewhich is opened by the pressure of the liquid in the hose 4 and closeswhen the pressure is reduced. Alternatively, the restrictor valve 9 maybe of a solenoid-operated type.

The dispensing operation is controlled by a microprocessor-basedelectronic controller which is mounted on the hand piece 3, having anassociated slave circuit 34 on the power pack 1. The controller 10 andcircuit 34, both include transceivers 35, 35′ respectively for wirelesscommunication there between, preferably in the UHF band. In someinstances it may be desirable, however, to use a wired connection.Electrical power is provided to the hand piece 3 components through abattery 23. Alternatively, if a wired connection is provided, power maybe supplied from the power pack and the battery 23 may be omitted.

The user enters specific data concerning a particular dispensingoperation into the controller 10 by means of a keypad 12 on the handpiece 3. The hand piece 3 also includes a trigger 22 to actuate thedispenser 100. The controller 10 also has an alphanumeric display 11 toprompt the user through the associated program, and to provideinformation to the user during the dispensing operation. As will bediscussed, the controller 10 monitors various system operatingparameters, and controls the operation of the motor 6 to achieve adesired pre-programmed dispensing operation.

A precisely known volume of liquid is displaced with each revolution orfraction of revolution of the pump drive shaft 21. A transducer 13 iscoupled to sense the rotation of the pump drive shaft 21 and providethis information to the electronic controller 10 via the circuit 34 andtransceivers 35, 35′. Once the system 100 is primed, the controller 10is then able to precisely control the amount of dispensed liquid bymonitoring the rotation of the drive shaft 21. The transducer 13 can beone of several types such as a passive variable reluctance magnetictransducer, or a Hall effect device.

In operation the user first connects the container coupling 15 to theuser's container 24. The electronic controller 10 initiates a series ofsystem diagnostics and if any of the diagnostics fail, an error messageis displayed on the display 11 and the controller 10 is disabled

Prior to recording the amount of liquid being pumped, the discharge hose4 must be primed. During priming of the discharge hose 4, air within thehose 4 is forced through the restrictor valve 9, and this volume of airwill not be applied to the desired dose amount. The hose 4 is preferablyreasonably short, as when it is fitted to a back pack mounted container(not shown) for use in the field. The hose 4, however, may be lengthy,as when used with a remotely located container. The priming may beaccomplished by pressing a prime button (not shown) on the power pack 1which causes the pump 5 to run. As the discharge hose 4 fills withfluid, air is displaced through the restrictor valve 9 into theatmosphere. Once the prime is detected visually by the user, who can seeliquid being ejected, a signal is sent to the electronic controller 10,the gear pump 5 is stopped, and the integrity tests continued.Alternatively, means such as a reed switch (not shown) may be employedto sense the presence of liquid and indicate this to the controller 10.

After successfully completing all the system integrity tests, thedisplay 11 will indicate the dispenser 100 is ready for operation. Theuser now is able to scroll the display 11 through a menu ofpre-programmed functions. He may enter a dose size, a dose (ordischarge) rate, and other such functions as allowing for the volumeunits displayed to be changed. Once the correct dose amount has beenentered, the trigger 22 is pressed to dispense the liquid. Thecontroller 10 starts the motor 6 and the gear pump 5 begins to pumpliquid from the container 24. As previously mentioned, the transducer 13senses the rotation of the gear pump drive shaft 21 and transmits theinformation to the controller 10 which records the volume of liquidbeing pumped, the controller 10 stopping the transfer when the desireddoes has been dispensed

The controller 10 may be recalibrated if a fluid of a differentviscosity is to be pumped. The supplier can also zero a running totalwhich is held in the control memory unit and may include the totalnumber of doses and their volume since the counter was last reset.

A drain cycle may be initiated by the user to drain the line, in orderthat the system may be used to deliver a different liquid. The inlethose 8 is disconnected by way of the coupling from the container 24, andthe motor 6 is then run (by pressing the prime button (not shown) on thepower pack 1) to draw air through the pump 5 and thereby displace theliquid from the hose 4. As when priming the device 100, the user maydirect the liquid into the container 24.

FIG. 2 illustrates the top view of one embodiment of a drench gun inaccordance with the present invention.

The drench gun 201 has an inlet 202 which receives liquid received bythe pump, and an outlet 203 which is attached to an appropriate nozzle,needle and the like.

The top of the drench gun has a screen 204 which can display variousinformation and menus allowing the operator to select modes of operationin the like.

A number of keys generally indicated by arrow 205 enable the operator toenter information and select control functions from a menu as required.

FIG. 3 is a diagramatic representation showing the connection of a backpack drench reservoir 301 connected by tubing 302 to a pump 303. Thelength of the tubing is not representative of actual lengths which mayvary considerably.

The pump 303 is connected by a tubing 304 to the inlet of the drench gun305. An electronic connection 306 is also present between the drench gun305 and the pump 303. This electronic connection is a means by which thedrench gun conveys control operations to the pump.

Aspects of the present invention have been described by way of exampleonly and it should be appreciated that modifications and additions maybe made thereto without departing from the scope of the appended claims.

1. A device for dispensing liquid which includes a hand piece for dispensing the liquid, a variable speed pump for pumping the liquid, communication means which enables the operator of the device to alter the speed of the pump to any one of a number of pre-programmed variable speeds, and a controller having an automated priming routine, wherein the hand piece includes a screen, and wherein a valve is situated between a fluid reservoir connected to the device and the pump.
 2. A device as claimed in claim 1 wherein the liquid is drench.
 3. A device as claimed in claim 1 wherein the hand piece is a drench gun.
 4. A device as claimed in claim 1 wherein the pump is a positive displacement pump.
 5. A device as claimed in claim 4 wherein the pump is a pump gear.
 6. A device as claimed in claim 1 wherein the hand piece includes the communications means.
 7. A device as claimed claim 1 wherein the hand piece includes a key pad.
 8. A device for dispensing liquid as claimed in claim 1 which further includes control means for enabling the operator to indicate to the device the environment in which the device is operating whereby the pump speed is caused to be adjusted accordingly.
 9. A device as claimed in claim 8 including control means for enabling the operator to indicate to the device a type of liquid to be dispensed whereby the pump speed is caused to be adjusted accordingly.
 10. A device as claimed in claim 9 wherein the type of liquid is chosen according to viscosity.
 11. A device as claimed in claim 10 wherein the type of liquid is chosen according to pre-programmed names.
 12. A device as claimed in claim 8 which can transmit and receive data.
 13. A device as claimed in claim 12 which includes a mobile phone.
 14. A device as claimed in claim 1 including volume indicators, wherein during the priming routine volume indicators on the device are deactivated.
 15. A device as claimed in claim 1 including a flow valve associated with the hand piece.
 16. A method of calibrating the volume of liquid dispensed by a device as claimed in claim 1, comprising the steps of: a) inputting into the device a desired volume of liquid to be dispensed; b) dispensing a volume of liquid from the device accordingly; c) measuring independently the actual volume dispensed; d) inputting into the device the actual volume dispensed or a comparative volume with a desired volume inputted in step a); and e) using the differential between the desired volume and the actual volume to calibrate the operation of the device over a range of volumes. 